The present disclosure relates to a nozzle for generating a high-pressure jet of a flowable nozzle for generating a high-pressure jet of a flowable medium, having a nozzle body and a nozzle disk which is embedded in the nozzle body in a recess. The nozzle body includes an axial nozzle bore which leads into at least one of an inlet and an outlet bore.
Such a nozzle is a component of a nozzle head which is used, for example, as a water jet nozzle in the high-pressure water jet technology field. Such a water jet nozzle is used, for example, for the cleaning of surfaces, the removal of coatings, the roughening of surfaces as well as the cutting and separating of materials.
For generating the high-pressure jet, the pressure generated by a pump in a volume flow of the medium is converted by a diminishing of the cross-section of the nozzle into a jet, preferably a liquid jet, having a high velocity. Water is normally used as the liquid. The generated pressures can amount to up to 4,000 bar and more, while the velocity is at up to 900 m/s.
Because of the resulting extremely high stressing of the nozzle disk, it is known from German Patent Document DE 94 19 809 U1 to produce this nozzle disk of a sapphire.
However, for obtaining a fairly acceptable service life, it is necessary to machine the nozzle disk as well as the recess, in which it is disposed, within very narrow tolerance limits with respect to the parallelism of the contact surfaces, the concentricity and the angularity as well as the dimensional accuracy. Apart from the fact that this can be done only at considerable manufacturing expenditures, even the low tolerances result in an extremely high stressing of the nozzle disk during the operation, which has a considerable influence on the service life.
Although it is not explicitly mentioned in German Patent Document DE 94 19 809 U1, in practice, the nozzle disk is provided with a sealing ring which is made of a nonferrous heavy metal alloy or of a plastic material and which seals the nozzle disk off with respect to the lateral wall area of the recess of the nozzle body.
However, the sealing ring is not capable of laterally supporting the nozzle disk, as would be required for absorbing tensions acting upon the nozzle disk, which tensions are generated by the high internal pressure in the nozzle bore. This non-existing radial support of the nozzle disk frequently leads to cracks and breaks during the operation, which results in dangerous situations, particularly when such nozzles are used in manually guided tools, such as spray guns or the like. As a result of the abrupt relaxation of the pressure during the breaking of the nozzle disk, the recoil power rises unexpectedly and unacceptably high, which may endanger the user of the spray gun.
In the case of the known nozzle, an axial prestressing force is applied to the nozzle disk as well as the nozzle body by way of a pressure screw. In this case, the force is guided to the nozzle body by way of the nozzle disk and the sealing ring.
However, this requires that corresponding height tolerances of the components are observed at high manufacturing expenditures. Nevertheless, an exceeding of the tightening torque on the pressure screw may result in a breaking of the brittle nozzle disk. This occurs relatively frequently because many nozzles are used and mounted under rough operating conditions, for example, at construction sites for the renewal of concrete.
The above-mentioning absent radial support of the nozzle disk also leads to high stress caused by dirt particles situated in the jet liquid which, when impacting on the assigned face of the nozzle disk, may also result in cracks with the above-described effects.
The present disclosure relates to a nozzle that may be produced more easily, that may have its service life prolonged, and that may have its operational reliability improved.
Thus, the present disclosure includes a nozzle for generating a high-pressure jet of a flowable medium, having a nozzle body and a nozzle disk which is embedded in the nozzle body in a recess. The nozzle body includes an axial nozzle bore which leads into at least one of an inlet and an outlet bore. The nozzle disk rests under compressive strain on contact surfaces of the recess.
The nozzle disk rests in the recess of the nozzle body in a virtually fixedly clamped-in manner, specifically in all stress situations possible during the operation of the nozzle.
In particular, effective radial forces, which result from the internal operating pressure within the nozzle bore, are directed directly onto the nozzle body. As a result, the nozzle disk becomes extremely resistant, so that a sudden crack formation or breaking is virtually excluded. The sensitivity with respect to dirt particles is also considerably reduced.
The nozzle body with the inserted nozzle disk is produced as a constructional unit and can be assembled such that no direct pressure forces act upon the nozzle disk during the assembly, for example, by a pressure screw or an inflow body operating in this manner.
The nozzle disk can be arranged in the interior of the nozzle body. This means that the nozzle disk is enclosed on all sides by the nozzle body.
Applied tension forces for fixing the nozzle body are thereby guided exclusively into the nozzle body.
This is also the case when the nozzle disk rests in the recess made on the face-side in the nozzle body. The inflow body, as the pressure piece, braces the nozzle body against a housing bottom, and the tension pressure originating from the inflow body is guided outside the nozzle disk into the nozzle body.
The nozzle body is produced by sintering or casting, in which case the nozzle disk is inserted beforehand so that it is completely enclosed by the material of the nozzle body after the casting or sintering.
As a result, a special machining precision with respect to the nozzle disk is not necessary which naturally saves expenses.
The nozzle body material, into which the nozzle disk is first embedded without any nozzle bore, is preferably corrosion-resistant and of a high strength.
By the sintering process or the casting, high constant compressive strain is applied to the contact surfaces of the nozzle disk, which compressive strain results in favorable operation of the nozzle.
After the termination of the sintering or casting, the exterior surfaces or sealing surfaces of the sealing body are produced, and an exit bore and possibly an entry bore and the nozzle bore are provided. As a result, a high concentricity is reached which leads to an optimization of the medium jet emerging from the nozzle.
Since an operationally caused breaking of the nozzle disk is virtually excluded, the operational reliability for the user may be increased in comparison to the known nozzle. Furthermore, the service life may also be prolonged, and may rise additionally because of the fact that the nozzle body with the embedded nozzle disk has a mirror-symmetrical construction in the longitudinal as well as the transverse axial direction. This permits a turning of the nozzle body in the event that the inlet area of the nozzle bore has been worn as a result of the operation. In this case, the nozzle body with the enclosed nozzle disk is only turned by 180°, so that the previous outlet side of the nozzle bore will now form the inlet side.
The nozzle disk can include a mechanically resistant ceramic material, preferably a sapphire, a ruby, a polycrystalline diamond or a mixed ceramics.
In addition to the above-mentioned possibility of embedding the nozzle disk by casting or sintering the nozzle body, there is also the possibility of soldering the nozzle disk to the nozzle body, preferably by means of hard-soldering.
In each case, the robust construction of the nozzle also permits the building-in of fan jet geometries of the nozzle bore, which may then have a cross-section which deviates from the circular shape, for example, an elliptical or rectangular shape. To this extent, the present disclosure envisions an expanded field of usage.
For prolonging the service life, in addition to the above-mentioned turning possibility of the nozzle body, the nozzle bore can be refinished, particularly in the area of the entry edge, so that, on the whole, an improvement may be obtained from an industrial management point of view.
Additional aspects of the present disclosure are included in the subject matter of the dependent claims.
Other aspects of the present disclosure will become apparent from the following descriptions when considered in conjunction with the accompanying drawings.